Bump ansys-sphinx-theme from 0.5.2 to 0.6.0 in /requirements

Bumps [ansys-sphinx-theme](https://github.com/ansys/ansys-sphinx-theme) from 0.5.2 to 0.6.0.
- [Release notes](https://github.com/ansys/ansys-sphinx-theme/releases)
- [Commits](ansys/ansys-sphinx-theme@v0.5.2...v0.6.0)

---
updated-dependencies:
- dependency-name: ansys-sphinx-theme
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements/requirements_docs.txt

@@ -1,6 +1,6 @@
 Sphinx==5.2.2
 ansys-mapdl-reader==0.52.0
-ansys-sphinx-theme==0.5.2
+ansys-sphinx-theme==0.6.0
 grpcio==1.43.0
 imageio-ffmpeg==0.4.7
 imageio==2.22.0